01-24-2018, 08:28 PM
Discussing weather is very difficult. It’s a complex subject. It is hard not to be long winded- Sorry! The last thing I need is negative comments- you can save those as I’m hoping to move soon. I used to do Puna Weather on FB but I don't do that anymore.
I had one of the best careers possible, I have 54 years of weather observing on my resume- 13 years here. And I’ll share some interesting observations from this last storm and from the many storms before it.
Hawaii gets about 15 North Pacific cold fronts a year that make it to Kauai. Of these about 10 make it all the way to the BI. They usually move from NW to SE. This one was unusual in that it moved from North to South directly- more of a springtime pattern usually and by then they’re usually much weaker (much less temperature differential between the air masses). It was a beauty too as it stretched from here all the way to Baja. Less than a week ago much of this air was above the Arctic Circle.
As the cold air plunges South- nothing’s really going to stop it except for dissipation or it modifies so much that it loses it’s temperature differential or the mechanism making it move South. That is until it encounters the BI.
The atmosphere acts much like a fluid. Observing these cold air masses moving South past the BI I have observed that much like a rock in a stream, the cold air piles up behind our rock. Once here the rock actually helps to stop it from modifying as the ocean is the great modifier. Land is a much less modifier. Good place for cold air to hang- right over our heads!
The strength and depth of this cold air will determine how heavy and long lasting the rain is. Remember those times when it just rained and rained? It was because of this cold air stuck here.
There is a reinforcing process that happens here too. When warm air moves North it rises over this cold air and this pushes the warm air higher, this in turn creates a downdraft of cold air plunging vertically down- what goes up has a corresponding equal downdraft- not equal= big storm. Ever notice those cool breezes when the heavy rain squall comes thru? These breezes could be coming from high altitudes.
Weather does not happen in a vacuum and for every weather action there is a corresponding counter action.
Rising warm moist air moving North over this cold air and with orograhpic forcing will create high rainfall rates- much higher than over the nearby ocean.
To illustrate the effect our rock has, one only has to look at average rainfall over the open ocean at our Latitude and Longitude. Only about 20-25 inches of rain falls a year over the nearby ocean but if you look at the BI you’ll see places that get well more than 100 inches and some places can get more than 300 inches some years.
This cold air plunging South always creates the worst weather here at this time of year. From excessive rainfall to high winds- it’s precisely the temperature differentials that creates the storms. These cold air bubbles are usually under forecasted. Tomorrow will be a case in point.
I’ll be watching tomorrow as this cold air moving South over the weekend created a pushback- came thru Sunday and Monday. I call it a rubber band effect. Now we have another pushback coming and with cold air still here-we could get a heavy weather day tomorrow. Enjoy the show on Thursday!
There also is a co-relation to how much this happens during one season and this can have an effect for a very long time, even lasting into different seasons. But that’s another discussion.
And when you have cold air trapped against our rock and warm moist air moving North the rain will not stop until either the cold air modifies out or the warm air wins out.
You can follow the cold air trend here;
https://tinyurl.com/yd2cesd5
In meters-use the Mouseover effect. Notice what the Freezing Level is doing over time over Hawaii and nearby.
I had one of the best careers possible, I have 54 years of weather observing on my resume- 13 years here. And I’ll share some interesting observations from this last storm and from the many storms before it.
Hawaii gets about 15 North Pacific cold fronts a year that make it to Kauai. Of these about 10 make it all the way to the BI. They usually move from NW to SE. This one was unusual in that it moved from North to South directly- more of a springtime pattern usually and by then they’re usually much weaker (much less temperature differential between the air masses). It was a beauty too as it stretched from here all the way to Baja. Less than a week ago much of this air was above the Arctic Circle.
As the cold air plunges South- nothing’s really going to stop it except for dissipation or it modifies so much that it loses it’s temperature differential or the mechanism making it move South. That is until it encounters the BI.
The atmosphere acts much like a fluid. Observing these cold air masses moving South past the BI I have observed that much like a rock in a stream, the cold air piles up behind our rock. Once here the rock actually helps to stop it from modifying as the ocean is the great modifier. Land is a much less modifier. Good place for cold air to hang- right over our heads!
The strength and depth of this cold air will determine how heavy and long lasting the rain is. Remember those times when it just rained and rained? It was because of this cold air stuck here.
There is a reinforcing process that happens here too. When warm air moves North it rises over this cold air and this pushes the warm air higher, this in turn creates a downdraft of cold air plunging vertically down- what goes up has a corresponding equal downdraft- not equal= big storm. Ever notice those cool breezes when the heavy rain squall comes thru? These breezes could be coming from high altitudes.
Weather does not happen in a vacuum and for every weather action there is a corresponding counter action.
Rising warm moist air moving North over this cold air and with orograhpic forcing will create high rainfall rates- much higher than over the nearby ocean.
To illustrate the effect our rock has, one only has to look at average rainfall over the open ocean at our Latitude and Longitude. Only about 20-25 inches of rain falls a year over the nearby ocean but if you look at the BI you’ll see places that get well more than 100 inches and some places can get more than 300 inches some years.
This cold air plunging South always creates the worst weather here at this time of year. From excessive rainfall to high winds- it’s precisely the temperature differentials that creates the storms. These cold air bubbles are usually under forecasted. Tomorrow will be a case in point.
I’ll be watching tomorrow as this cold air moving South over the weekend created a pushback- came thru Sunday and Monday. I call it a rubber band effect. Now we have another pushback coming and with cold air still here-we could get a heavy weather day tomorrow. Enjoy the show on Thursday!
There also is a co-relation to how much this happens during one season and this can have an effect for a very long time, even lasting into different seasons. But that’s another discussion.
And when you have cold air trapped against our rock and warm moist air moving North the rain will not stop until either the cold air modifies out or the warm air wins out.
You can follow the cold air trend here;
https://tinyurl.com/yd2cesd5
In meters-use the Mouseover effect. Notice what the Freezing Level is doing over time over Hawaii and nearby.